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.TH CRYPT 3C "Sep 28, 2004"
.SH NAME
crypt \- string encoding function
.SH SYNOPSIS
.LP
.nf
#include <crypt.h>

\fBchar *\fR\fBcrypt\fR(\fBconst char *\fR\fIkey\fR, \fBconst char *\fR\fIsalt\fR);
.fi

.SS "Standard conforming"
.LP
.nf
#include <unistd.h>

\fBchar *\fR\fBcrypt\fR(\fBconst char *\fR\fIkey\fR, \fBconst char *\fR\fIsalt\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBcrypt()\fR function encodes strings suitable for secure storage as
passwords. It generates the password hash given the \fIkey\fR and \fIsalt\fR.
.sp
.LP
The \fIkey\fR argument is the plain text password to be encrypted.
.sp
.LP
If the first character of \fIsalt\fR is "$", \fBcrypt()\fR uses
\fBcrypt.conf\fR(5) to determine which shared module to load for the encryption
algorithm.  The algorithm name \fBcrypt()\fR uses to search in \fBcrypt.conf\fR
is the string between the first and second "$", or between the first "$" and
first "," if a "," comes before the second "$".
.sp
.LP
If the first character of \fIsalt\fR is not "$", the algorithm described on
\fBcrypt_unix\fR(7) is used.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, \fBcrypt()\fR returns a pointer to the encoded
string. Otherwise it returns a null pointer and sets \fBerrno\fR to indicate
the error.
.sp
.LP
The return value points to static data that is overwritten by each call.
.SH ERRORS
.sp
.LP
The \fBcrypt()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 11n
An entry in \fBcrypt.conf\fR is invalid.
.RE

.sp
.ne 2
.na
\fB\fBELIBACC\fR\fR
.ad
.RS 11n
The required shared library was not found.
.RE

.sp
.ne 2
.na
\fB\fBENOMEM\fR\fR
.ad
.RS 11n
There is insufficient memory to generate the hash.
.RE

.sp
.ne 2
.na
\fB\fBENOSYS\fR\fR
.ad
.RS 11n
The functionality is not supported on this system.
.RE

.SH USAGE
.sp
.LP
The values returned by this function might not be portable among
standard-conforming systems. See \fBstandards\fR(7).
.sp
.LP
Applications should not use \fBcrypt()\fR to store or verify user passwords but
should use the functions described on \fBpam\fR(3PAM) instead.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.sp
.LP
.BR passwd (1),
.BR crypt_genhash_impl (3C),
.BR crypt_gensalt (3C),
.BR crypt_gensalt_impl (3C),
.BR getpassphrase (3C),
.BR pam (3PAM),
.BR passwd (5),
.BR policy.conf (5),
.BR attributes (7),
.BR crypt_unix (7),
.BR standards (7)
